1. Field of the Invention
This invention relates to a ladder scaffold composed of a scaffold plank, a ladder and a hanger supporting one end of the scaffold plank from such ladder.
2. Prior Art
U.S. Pat. No. 1,351,795, issued Sept. 7, 1920, discloses an attachment for ladders for hanging a scaffold plank from and between ladders spaced apart a distance approximately equal to the length of the scaffold plank. The attachment is intended to support each end of the scaffold plank from two rungs of a ladder but it would be very difficult to adjust the device so that the load of the scaffold plank would be shared equally by each of two rungs. At best great care would be required to provide the intended adjustment and alteration of loading on the scaffold plank could alter the load distribution between the rungs.
U.S. Pat. No. 2,637,517, issued May 5, 1953, discloses a ladder bracket having some features similar to those of the ladder bracket of the present invention but such bracket is considerably more complicated and would be more difficult to use.
U.S. Pat. No. 2,619,390, issued Nov. 25, 1952, shows a scaffolding plank having hooks at the ends somewhat similar to the scaffold plank used in the present invention but this patent requires special ladders to support the scaffold plank.
U.S. Pat. No. 4,542,874, issued Sept. 24, 1985, discloses a stop lug on the end of a plank supporting arm which is generally similar to the stop lug used in the present invention.